This document provides an introduction to switchgears. It defines switchgear as equipment used for switching, protection, control and isolation in a power system. The principal switchgears are the main equipment for switching and isolating circuits, while auxiliary switchgears assist with control, measurement, protection and fault clearing. Examples of principal switchgears include circuit breakers, isolators, and switches, while auxiliary switchgears include protection relays, current and voltage transformers, and tripping units. The document also describes the functions and operation of circuit breakers.